With most of the election districts reporting, Christie had 55 percent of the vote to 42 percent for Steve Lonegan, the anti-tax former mayor of Bogota, a small town in Bergen County, The Star-Ledger of Newark reported. A third candidate, Assemblyman Rick Merkt, had less than 3 percent.
On the Democratic side, Gov. Jon Corzine was the clear winner with 78 percent of the vote against three little-known candidates.
Christie, who served as U.S. attorney from 2002 to December, was the establishment choice, with the largest campaign war chest and a 20-point lead in recent polls. Lonegan has a strong following among conservatives.
New Jersey this year is a bright spot for Republicans after a series of bruising elections. Corzine, completing his first term, trails Christie in head-to-head polls and could become the first Democrat to lose a statewide race since 1997.
"Jon Corzine joins that long list of politicians who over-promised and under-delivered," Christie said as he declared victory. "I will be a very different governor. I will wake up every morning with one mission -- how do we make government smaller. How do we give tax money back to New Jersey."
The state's financial troubles and Corzine's attempts to deal with them by raising highway tolls and taxes and cutting services have made him unpopular with voters. But the Democrats have a strong edge in registrations, and Corzine, a former Goldman Sachs chief executive officer with a large personal fortune, is already running ads attacking Christie.
Susan Sarandon 'very excited' about daughter's pregnancy
Scarlett Johansson steps out with fiance after pregnancy reveal